1. Field of the Art
Embodiments of the present invention generally relate to manufacturing surgically implanted electronics, in particular, an electrode array that connects with tissues, such as the retina of an eye.
2. Description of the Related Art
Age-related macular degeneration (AMD) and retinitis pigmentosa (RP) are two most common outer-retina degenerative diseases of the human eye. There is promise in the use of retinal prostheses in order to allow people afflicted with the diseases to see. Retinal prostheses, which bypass the defective outer-retina photoreceptors and electrically stimulate the inner-retina neurons directly, have allowed some blind people with AMD and RP to perceive light.
It is recognized that these early prostheses only involve a very small number of stimulating electrodes on the neurons. To realize facial recognition or large-sized letter reading, next-generation retinal prosthetic devices may use 1024 or more stimulating electrodes. A 1024-electrode implant can be configured as a 32-by-32 square array of electrodes or with different numbers of electrodes in rectangular, circular, or other shapes.
Due to surgical incision limitations on eyeballs, and to match the size of the macula lutea, the 1024 stimulating electrodes should be arranged on a small area within 7 millimeters (mm)×7 mm of one another. Therefore, each electrode should be small enough to fit in the allotted area and give an acceptable spatial resolution. However, smaller electrodes, because they are small, suffer from high impedance. High impedance leads to high charge densities, which may result in damage to tissue.
There is a need in the art for improved biocompatible electrodes and manufacturing techniques.
The subject matter discussed in the background section should not be assumed to be prior art merely as a result of its mention in the background section. Similarly, a problem mentioned in the background section or associated with the subject matter of the background section should not be assumed to have been previously recognized in the prior art. The subject matter in the background section merely represents different approaches, which in and of themselves may also be inventions.